1. Field of the Disclosure
The present invention relates to semiconductor devices, and, more particularly, to a high voltage semiconductor device.
2. Discussion of the Related Art
Circuits used for LSI (large-scale integration) for driving a flat display device, such as LCD (liquid crystal display device), PDP (plasma display panel), OLED (organic light-emitting diode), LSI for automobile, LSI for OA (office automation) and peripheral devices, and a motor driving LSI may have a high voltage device and a low voltage logic device integrated within one chip.
PMIC (Power Management Integrated Circuit) products each having a high voltage device and a low voltage logic device integrated within one chip are developing day by day, and fields of application thereof are increasing.
In general, in order to form a high voltage device, a well forming step is performed and an extended drain region is formed for the high voltage device before a logic device is formed. Or, a well for a logic device can be used together with a well for the high voltage device at one device channel region.
However, the steps for forming the high voltage device can result in an increase in the number of fabrication steps, which is liable to increase a production cost. The use of a well for a logic device together with a well for the high voltage device at one device channel region can cause instability of a device threshold voltage. Moreover, the integration of a high voltage device and a low voltage logic device on one chip may cause limitation in making a device smaller.